The AMORE Score for Predicting the 5-Year Risk of Hemorrhagic Stroke in Asymptomatic Moyamoya Disease

INTRODUCTION: The aim of this study was to establish the score for predicting the 5-year risk of hemorrhagic stroke in patients with asymptomatic moyamoya disease (MMD) using the Asymptomatic Moyamoya Registry (AMORE) data and to evaluate its reproducibility. METHODS: The AMORE study was a prospective cohort study that recruited participants from 18 centers in Japan. A total of 103 patients completed the 5-year follow-up and of these, 6 patients experienced hemorrhagic stroke. According to the results of multivariate analysis, we selected age ≥46 years, grade-2 choroidal anastomosis, and microbleeds as variables in the prediction model. The cumulative rates of hemorrhagic stroke were estimated per hemisphere using the Kaplan-Meier method. Nonparametric bias-corrected confidence intervals (CIs) based on the Bootstrap sample were calculated to assess the reproducibility of the 5-year risk of hemorrhagic stroke. RESULTS: We created the AMORE score (0-3 points) to estimate the 5-year risk of hemorrhage with 1 point for each of age ≥46 years, grade-2 choroidal anastomosis, and microbleeds. The AMORE score was applied to a total of 135 MMD hemispheres. The 5-year risk of hemorrhagic stroke per hemisphere was 1.8%, 1.6%, 15.4%, and 50.0% for AMORE scores of 0, 1, 2, and 3, respectively. The cumulative rate of hemorrhagic stroke for AMORE score 3 was significantly higher than for AMORE score 0 (hazard ratio [HR], 38.7; 95% CI, 3.45-433; p = 0.003) and score 1 (HR, 41.8; 95% CI, 3.74-468; p = 0.002). The corresponding 90% CIs were 0%-5.6%, 0%-5.2%, 0%-38.5%, and 0%-100%, and the corresponding 80% CIs were 0%-4.7%, 0%-4.5%, 5.9%-33.3%, and 23%-100% for AMORE scores 0, 1, 2, and 3, respectively. CONCLUSION: The 5-year risk of hemorrhagic stroke in patients with asymptomatic MMD can be adequately estimated using the AMORE score.